1. Field of the Invention
The present invention relates to a communication network analysis apparatus in a multi-layered communication system and a method using the apparatus, and more specifically, to a communication network analysis apparatus in a building automation and control system, a communication method, and a protocol conversion method using the same.
2. Description of the Related Art
A communication network analysis apparatus and a protocol used herein are preferably applied to a building automation and control system. Hereinafter, BACnet will be described as an example of the building automation and control system.
BACnet is an abbreviation of ‘A Data Communication Protocol for Building Automation and Control Network’, which means a communication protocol for building automation and control adopted as an industry standard in international standard ISO 16484-5 and Korean standard KS X 6909.
As requirements on integrated building automation and control systems are increased recently, instances of application and development of an integrated building management system using BACnet are gradually increased.
BACnet is provided with a plurality of layers including a data link layer.
The BACnet MS/TP protocol, which is one of six data link layer protocols, is a communication protocol dedicated to a data link layer that uses an EIA-485 half-duplex communication method.
A BACnet MS/TP communication network, to which the BACnet MS/TP protocol is applied, is mainly used in a building automation and control system to construct low-cost high-efficiency field communication networks for connecting sensors, actuators, field controllers, building controllers, and the like.
A BACnet visual test shell (VTS), which is a general-purpose BACnet communication test program provided by the BACnet manufacturer association (BMA), is mainly used for BACnet interoperability tests when a BACnet-protocol-based building automation and control apparatus is developed.
A conventional communication network analysis apparatus using a BACnet VTS and a communication method using the communication network analysis apparatus have following problems.
First, there is a problem in that only a unidirectional monitoring function for the BACnet MS/TP protocol is provided. It means that the BACnet VTS provides a sniffing function for the MS/TP frames generated on a BACnet MS/TP communication network. Even though the BACnet VTS can generate and transmit a certain MS/TP frame on a BACnet MS/TP communication network, it is insufficient to perform complicated bidirectional communication interoperability tests.
Second, there is a problem in that the BACnet VTS could not maintain the function of MS/TP master node state machine. Only the BACnet MS/TP master node can voluntarily initiate a service request when the master node holds the token. BACnet VTS is not able to act as a MS/TP master node on the BACnet MS/TP communication network. Therefore, there is a problem in that bidirectional peer-to-peer communication interoperability tests can not be performed.]